Cookies are typically made from flour, sugar, fat or shortening and a suitable flavoring component. Common flavorings may include chocolate, cocoa powder, chocolate liquor or chocolate flavor chips. The inclusion of these flavorings has the disadvantage of producing bloom on the surface of the cookie in some cookie formulations. The bloom on the cookies appears as a white haze or deposit on the surface of the cookie. The bloom may appear as discrete particles, although usually it appears as a continuous layer. The cookie, and particularly dark chocolate cookies, tend to loose their detail and color as a result of the bloom. Bloom may also be a serious problem in high moisture cookies and soft cookies where the bloom generally forms during cyclic temperature changes.
The bloom on the surface of the cookies is the result of the formation of fat crystals and is typically referred to as fat bloom. Bloom may occur in many fat systems, but is normally most noticeable in chocolate and cookies containing chocolate or cocoa powder and chocolate liquor. It is also believed that cookies of high moisture content are more susceptible to fat bloom than cookies with lower moisture. Fat bloom may also occur in chocolate chips or chocolate products where the chocolate has not been properly tempered or which has been subjected to sudden cooling. Bloom may also occur in chocolate cookies and chocolate chip cookies made with a high portion of liquid shortening.
In a typical cookie manufacturing process, after baking the cookies are cooled below ambient temperature to solidify fats and thus aid in packaging of the product. It is believed that during this cooling step, cocoa butter, a polymorphoric fat, in the product solidifies into an initial crystalline structure that has a melting point at or below ambient temperature (approximately 65.degree. F.). Due to the formation of a eutectic with certain vegetable shortenings commonly used in cookies this melting temperature may even be further lowered. During storage, the cookie reaches ambient temperature which causes some of the cocoa butter to liquify. The liquified cocoa butter then migrates to the surface of the cookie where it recrystallizes to a more stable crystal form and produces bloom. Bloom does not create any health risks or significantly influence the taste or texture of the product. The appearance of white haze of fat bloom is, however, unappealing and tends to make the product appear stale and unappetizing. The bloom often makes the cookies appear scuffed, damaged or defective.
Fat bloom is particularly noticeable in dark chocolate or fudge cookies which are made from a mixture of flour, sugar, water, fat or shortening, cocoa powder and/or chocolate liquor. The flavor of cocoa powder is generally strong, depending on the processing, and is used in small amounts compared to the other ingredients. Cocoa powder, however, generally contains about 10% by weight cocoa butter. Although chocolate cookies contain fairly low amounts of cocoa butter, the cocoa butter tends to promote fat bloom. Cocoa butter is different from most other fats in that it undergoes polymorphism in at least three different distinct polymorphic crystalline forms which is believed to be a contributing cause of fat bloom. The different crystalline forms of cocoa butter have different energies and melting points. The most unstable crystalline forms have the highest energy and melt at lower temperatures. The lower melting point fraction of the coco butter is believed to liquify during storage and migrate to the surface of the cookies where it recrystallizes into a more stable crystal form.
Bloom may also occur in creme-filled sandwich cookies where the fat can migrate between the filler and the cookie base cake. Fat migration between the components can result in interaction of the ingredients to change the color, texture and taste of the cookies.
Chocolate and fudge cookies containing cocoa powder and/or chocolate liquor are particularly prone to bloom when most vegetable fats are used as the shortening in the cookie base cake. It is believed that the bloom may be caused by an interaction of the fat in the cookie and the cocoa butter which inhibits rapid crystallization of the cocoa butter. Lard, however, when used as the cookie shortening has been found to resist fat bloom in cookies which contain cocoa butter, except under extreme temperature changes. Lard does not exhibit polymorphic behavior and crystallizes quickly during cooling to a stable crystal form. It is believed that the lard, which has a relatively sharp melting point, causes the cocoa butter to crystallize rapidly on cooling. The rapid crystallization of the cocoa butter is believed to produce small crystals and prevent fat bloom. Lard further has a fairly linear solid fat content between 65.degree. F. and 80.degree. F. unlike most other vegetable fats. In addition to preventing fat bloom, lard produces a texture and distinct flavor which is difficult to duplicate using vegetable shortenings. In recent years, however, consumer acceptance of lard in baked goods has diminished, resulting in efforts to find a suitable substitute for lard. Many of the substitutes for lard are subject to fat bloom.
Efforts to prevent fat bloom in cookies include, for example, the methods disclosed in U.S. Pat. No. 4,894,246. A low melting fat having a solid fat index of less than 13 at 80.degree. F. and which is liquid at about 100.degree. F. is added to a cookie dough containing chocolate chips. The low melting fat is added in an amount such that it comprises about 5% to 30% of the fat in the cookie. The low melting fat is reported to reduce the effects of fat bloom of the chocolate chips and the halo effect of bloom on the cookie around the chips.
The previous methods of reducing fat bloom on cookies are concerned primarily with the bloom from chocolate chips. These methods are not suitable for preventing bloom of dark cookies containing cocoa power or chocolate liquor where the cocoa butter is intimately mixed throughout the cookie. In addition, these methods are not able to duplicate the taste and texture of lard in cookies. There is accordingly a need for a suitable lard replacement in cookies containing cocoa butter in the form of cocoa powder or chocolate liquor.
The present invention provides a shelf-stable cookie which is resistant to fat bloom over extended times. The cookies are produced from partially hydrogenated soybean oil and/or cotton seed oil which are able to substantially duplicate the flavor and texture of chocolate or fudge cookies made from lard.